This invention relates to a step motor for use in an electronic timepiece and particularly to the use of induced currents generated in an electromagnetic coil for reducing the power utilized by such motors in stepping the rotor.
A problem encountered in conventional step motors utilized in electronic timepieces is the attenuation of the rotor after stepping same, caused by the driving pulses utilized to step the rotor. Heretofore, such attenuation has been prevented by providing a permanent magnet on the stator, or placing a permanent magnet between the rotor and the stator. The disadvantage of the former was that current pulses continued to be applied until the rotor was attenuated to some extent, the consequence thereof being a long pulse width and hence an increase in the current consumption of the motor. The disadvantage encountered in placing the permanent magnet between the rotor and the stator was the complexity of properly positioning the permanent magnet since the rotary angle through which the rotor is stepped as each pulse is applied thereto is doubled and the magnetic poles of the fixed permanent magnet are predetermined in advance.